The invention proceeds from a device on hand-held tool-driving machines for coupling pounding and/or drilling tools as well as from a tool and tool holder used with that device.
Such a device is known from EP- 433 876 A1, whereby the trapezoidal or rectangular coupling grooves on the tool shank and the corresponding coupling gibs on the tool holder have a limited wear allowance on their coupling flanks. Particularly in the case of tools having a large working diameter and in the case of powerful machines, the lands between the grooves or the gibs in the seating hole of the tool holder break off. Moreover, the rear flank of the trapezoidal or rectangular coupling grooves is loaded by hard torque thrusts, especially in the case of tilted chiseling work, and this results in notch effects that promote breakage of the gibs on the tool holder and of the lands between the grooves on the tool shank.
Furthermore, a chord-shaped recess on the tool shank is known from DE 42 11 533 A1, a recess which lies opposite an essentially trapezoidal groove for coupling. The chord-shaped recess is used for improvement of compatibility in that a tool shank of such a shape can be inserted in hand-held tool devices having coupling gibs of different widths on their tool holders. Coupling in this case, however, is effected is a very one-sided manner, almost solely on the opposite groove's coupling flank located in the drive direction, since the locking bodies of the tool holder absorb only a slight torque in the locking depressions on the tool shank assigned to them.